Thermal Behavior of Tropical Sea Cucumber of Isostichopus isabellae: Preliminary Issues

We investigated the growth, preferences, and thermal resistance of the sea cucumber Isostichopus isabellae to understand its thermal biology. Sixty individuals were kept in tanks at two temperatures (23 °C and 26 °C) for 30 days to determine their favorable maintenance temperature. Their survival rates and specific growth rates were measured to establish their ideal conditioning temperature in the laboratory. The sea cucumbers' thermal preference was evaluated over a gradient from 20 °C to 29 °C, and their behavior was monitored for 4 h. They preferred the temperature to which they were acclimated, aligning with the favorable temperature identified in this study. We did not find differences in the average weight loss between the two experimental temperatures. The highest survival rate (86%) was observed at 23 °C, which can be considered to be the most favorable maintenance temperature. The critical thermal maximum (CTMax) and minimum (CTMin) were determined by gradually heating or cooling the water until the sea cucumbers showed a loss of podia movement and body relaxation. CTMax was established at 36.5 ± 0.3 °C and CTMin at 8 ± 0.5 °C. Based on these results, Isostichopus isabellae could negatively respond to increased temperatures, so we recommend maintaining a favorable temperature of 23 ± 2.3 °C in captivity for its use in aquaculture.